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asperities
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Microscopic peaks found on all surfaces. Contact between asperities causes friction.
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axis
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An imaginary straight line passing through the center of an object. A round component such as a gear typically rotates around its axis. An axis also indicates the direction of a component's linear motion on a machine tool.
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ball screw
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A long, threaded device with reciprocating ball bearings that rotates to move components in a linear direction.
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belt drive system
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A system consisting of a belt and at least two fixed pulleys that transmit motion from one pulley to the other.
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centimeters per minute
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In the metric or SI system, the number of centimeters that a component travels in one minute (cpm).
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chain drive system
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A system consisting of a chain and sprockets that transmits motion from one sprocket to the other.
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drive gear
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The gear that receives energy from a power source, such as an electric motor. Drive gears transmit power to an intersecting driven gear to perform work.
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driven gear
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The gear that receives motion from the drive gear on a machine. Driven gears often turn tools or components.
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dynamometer
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A device used to measure an engine's horsepower or torque.
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efficiency
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A measure of the work output of a system versus the total work supplied to it.
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English system
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A standard system of measurements based on the inch, pound, and Fahrenheit degrees. English measurements are primarily used in the United States and England.
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foot-pound
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In the English system, the unit used to measure power, abbreviated as ft-lb.
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force
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The push or pull that gives energy to an object. A force changes an object's motion or state of rest.
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friction
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The resistance to relative motion between surfaces. Friction is caused by contact between surface asperities.
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gear ratio
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The relationship between the number of teeth on two meshing gears used to transmit motion. The gear ratio reflects the change in mechanical advantage resulting from the gears.
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horsepower
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A unit of power used to describe machine strength, abbreviated as hp. One horsepower equals 33,000 ft-lbs of work per minute, or 746 watts.
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inches per minute
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In the English system, the number of linear inches that a component travels in one minute (ipm).
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inertia
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The tendency of an object to remain at rest until acted on by a force.
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kinetic friction
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Friction between objects in motion. Kinetic friction is generally less than static friction.
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linear motion
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Motion that takes place along a straight line. Mechanical energy can take the form of rotary or linear motion.
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load
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The opposition to applied force, such as a weight to be carried or moved.
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lubricant
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A substance used to reduce friction between two surfaces.
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mass
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The amount of matter that is contained within an object.
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mechanical power
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Power that is transmitted through a mechanical system and used to perform work.
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metric system
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A standard international system of measurement based on the gram, liter, and meter. Also known as the SI system.
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Newton-meter
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In the metric system, the unit used to measure power and torque, abbreviated as N-m.
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peak horsepower
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The maximum horsepower a machine can exert, achieved at a certain rpm. After horsepower peaks, it will decrease with increasing rpm.
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peak torque
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The maximum torque a machine can exert, achieved at a certain rpm. After torque peaks, it will decrease with increasing rpm.
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pound-feet
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In the English system, the units used to measure torque, abbreviated as lb.-ft.
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power
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The rate at which work is accomplished. Power is expressed in ft-lbs. and is the result of the amount of work accomplished divided by the time it took to do the work.
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pulley
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A circular device that is used as a pair in belt drive systems to transmit motion.
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ram
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The main upper portion of a stamping press that slides up and down within the press frame during operation.
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revolutions per minute
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A unit of measurement that indicates the number of revolutions a machine component makes in one minute (rpm).
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SI system
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An abbreviation for the metric system. Since it is used worldwide, SI is the abbreviation for Systeme International, or International System in English.
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specification
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A description of the essential physical and technical properties of a machine. Specifications or "specs" often include torque and horsepower ratings.
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speed
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The amount of distance an object travels in a given period of time. Speed is used to measure both linear and rotational movement.
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sprocket
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A gear or wheel with metal teeth that meshes with the links of a chain. Sprockets are used in chain drive systems to transmit motion.
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static friction
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Friction between two objects in contact that are not moving. Static friction is generally greater than kinetic friction and must be overcome before an object can be set in motion.
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tension
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A pulling force that is directed away from the object and attempts to stretch or elongate the object. Tension affects belt and chain drive systems.
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thrust
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A force that occurs when an object is accelerated in one linear direction. Thrust can be expressed by the equation force = mass x acceleration.
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torque
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A force that produces rotation. Torque is measured in pound-feet in the English system and Newton-meters in the metric system.
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watt
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A unit used to measure power. 746 watts equal one horsepower.
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wear
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The gradual removal of material on a surface caused by contact between surface asperities.
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work
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The result of a force applied to an object and the distance through which the force is applied. In an equation, work is force multiplied by distance.
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worm
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A cylindrical, screw-shaped shaft that is used with a worm gear to transmit motion.
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worm gear drive
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A gear drive consisting of a long, cylindrical device with a spiraling groove that intersects with the teeth of a wheel-like gear. A worm gear drive is used to transmit motion between nonintersecting perpendicular shafts, and the cylindrical "worm" is always the drive gear.
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